Conventionally, when forming a permanent pattern such as interconnection pattern, a pattern forming material which is prepared by applying a photosensitive resin composition over a surface of a support, drying the support surface to form a photosensitive layer, and laminating a protective film on the photosensitive layer is used. For a method of producing such an permanent pattern, for example, a pattern forming material is laminated on a substrate such as a copper clad laminate on which a permanent pattern is to be formed while peeling off a protective film from the pattern forming material to form a laminate on the substrate surface, a photosensitive layer in the laminate is then exposed, and after the exposure, the photosensitive layer is developed to thereby form a pattern, and the pattern forming material is subjected to an etching treatment and the like, thereby a permanent pattern can be formed.
For the protective film, typically, a polyolefin film is used. However, in a polyolefin film, defective structure of protrusions called fish-eyes is observed. For this reason, regions of the photosensitive layer which make contact with fish-eyes residing in the protective film are pushed and get thinner, and when the photosensitive layer is exposed and developed, the photosensitive layer may cause pattern defects at the regions.
To solve the problem, a polyethylene film in which fish-eyes are reduced (see Patent Literature 1), and a pattern forming material using a film having substantially less fish-eyes as a protective film (see Patent Literature 2 to Patent Literature 4) have been proposed.
However, since a protective film that has substantially less fish-eyes and is excellent in smoothness excessively adhere to a photosensitive layer, such a protective film may cause wrinkles on a support and the photosensitive layer when successively subjected to a consecutive lamination step such as autocut lamination, and may cause a problem that static electric charge is generated when the protective film is peeled off from the pattern forming material.
Patent Literature 1 to Patent Literature 4 do not disclose, to solve these problems, a pattern forming material that is excellent in laminating property and chargeability can be obtained without degrading photosensitivity of the photosensitive layer and resolution by using a protective film of which the size and the number of fish-eyes are respectively limited within a certain range.
Summarizing the above, a pattern forming material that is capable of suppressing generation of wrinkles and static electric charge on a substrate in a lamination step in which the pattern forming material is laminated on the substrate as well as capable of forming a fine and precise pattern, a pattern forming apparatus provided with the pattern forming material, and a pattern forming process using the pattern forming material have not yet been provided so far, and further improvement and development are still needed.
Patent Literature 1 Japanese Patent Application Laid-Open (JP-A) No. 2000-273203
Patent Literature 2 Japanese Patent (JP-B) No. 3019075
Patent Literature 3 Japanese Patent Application Laid-Open (JP-A) No. 2003-228168
Patent Literature 4 Japanese Patent Application Laid-Open (JP-A) No. 2003-248320